Process of mordanting and dyeing wool



Patented Apr. 20, 102% FWQE.

FRANCIS C. TELEN, OF PENNS GROVE, NEW JERSEY, ASSIGNOR T0 E. I.VDU PONTDE I NEMOURS & COMPANY, OF WILMINGTON, DELAWARE, A

WARE.

No Drawing. .Application filed July 1,

To all whom it may concern:

Be it known that I, FRANCIS C. TnLEN, a citizen ofthe United States, anda resident of Penns Grove, in the county of Salem and State of NewJersey, have invented a certain new and useful Process of Mordanting andDyeing Wool, of which the following is a specification.

This invention relates to the mordanting of wool with chromium compoundsand the dyeing of the wool in the presence of the mordantin liquor. Oneof the essential features of my invention is the reduction of thechromium compound, for example, sodium bichromate, with lactic acid inthe absence of stronger acids such as sulphuric. Another importantfeature of my invention consists in adding the dye directly to themordanting bath.

As is well known, mordant dyestuffs, including the ortho-oxy-azo colors,form colored lakes with the metals. This fact is made use of in theapplication of these dyes, the most valuable and most extensively usedlakes of these colors being those of chromium. These chromium lakes areproduced on the fibre either by mordanti-ng the material with chromiumsalts and then dyeing with the particular color, or by using theso-called chromate, mono-chrome, metachrome, or after-chrome processes.When these colors are dyed in metal machines, especially machinesconstructed of iron, the formation of the valuable chromium lake isinterfered with by the presence of theiron, and in consequence, thedyeings are rendered valueless. It has therefore been customary to carryout the mordanting and dyeing operations in vessels made of wood orhaving a non-metallic inner surface.

One object of my invention is to provide a process of chrome-mordantingand dyeing which will permit the use of iron, or other metallic,vessels.

Another object of my invention is to improve on methods of applyingchrome colors, and especially chromable azo dyestufi's, whereby a greatsaving in time 'may be effected.

T have discovered that lactic acid combines to an eminently satisfactorydegree the ooarona'rron or DELA- PROCESS OF MORDANTING AND DYEING'WO'OL.

1921. Serial No. 481,982.

two properties of being a sufficiently strong reducing agent to reducebichromates without the assistance of other acids, and sulficiently weakto have no appreciable action on iron. It is possible that the avoidanceof injurious results from the presence of iron may be due to somepositive, instead of to a negative, behavior of the lactic acid, butthat the excellent results obtained are due to the inability of thelactic acid to attack metals such as iron seems most probable.

I have discovered, furthermore, that, ir respective of the type ofvessel used, a great economy intime may be effected by using lactic acidas the reducing agent for the bichromate, and, aftera short preliminarytreatment of the wool in the mordanting bath, adding the dyestufldirectly to said bath, the last step of the operation being anafter-chroming treatment.

My new process as carried out in an iron vessel may be illustrated bythe following example 100 lbs. of W001 are boiled with from dyeing iscontinued for one hour with the addition of organic or mineral acids(for example, sulphuric acid) to exhaust the color. The color is thenafter-chromed. in the same, or in a fresh, bath with 2 lbs. sodiumbichromate, one pound of sulphur acid and 4 lbs. of lactic acid for 30minutes. Where a fresh bath is used the bichromate, sulphuric acid andlactic acid are dissolved in from 1000 to 1500 lbs. of water, dependingupon the capacity of the dyeing machine used. The above steps ofmordantingand dyeing are preferably carried out with boiling solutions;if desired, however, the solutions may be maintained at a temperaturebetween about 90 and 100 C.

The above procedure represents a combined method of dyein andmordanting, and depends for its uti ity, on the partial reduction ofbichromate or other chromium pure shade. It also insures the samefullness and depth and the same fastness that would be obtained from thesame amount of color by any other method of chroming.

It will be readily appreciated by those versed in the art that thismethod marks a distinct improvement, in that it edects a great economyin time. By the older methods it is found necessary to mordant the goodsfor at least 11} hours in order to effect the complete reduction of thebichromate, and then the dyeing must be carried out in fresh liquor. Inmy process, this time is cut down, because after the reduction hasproceeded only a little way, the dyeing can be carried out in the sameliquor. The final after-chroming, as described in the example, is givenonly to insure the greatest possible fastness.

It will be understood that the process of using lactic acid with theexclusion of other stronger-acids to overcome the injurious action ofiron or iron salts is of general application in the .chrome-mordantingof Wool, and that the process, as regards the series of steps, may bepracticed with various dyes other than the azonaphthalene derivativeabove-mentioned. The conditions of operation given in the specificexample may also be varied considerably as will be evident to oneskilled in the art.

I claim:

.1. A process permitting the mordanting of wool with a bichromatesolution in a vessel provided with an inner metallic surface,- composed,at least in part, of a metal whose salts are capable of reacting withmo'rdant dyestuffs to form colored lakes which comprises treating thewool with a hot solution containing a bichromate and lactic acid butfree from an acid substantially stronger than lactic acid, said solutionduring at least part of said treatment being in contact with part ofsaid metallic surface.

2. The process which comprises treating wool/,with a boiling solutioncontaining a bichromate and lactic acid but free from an acidsubstantially stronger than lactic acid, said solution during at leastpart of said treatment being in contact with a metal whose salts arecapable' of reacting with mordant dyestufis to form colored lakes.

3. The process .which comprises treating wool with a hot solutioncontaining a bichromate and lactic acid but free from an ac dsubstantially stronger than lactic acid. said solution during at leastpart of said treatment being in contact with metallic 11011.

acids.

eeaosr t. The process which comprises subjecting wool in an iron vesselto the action of a solution containing an alkali-metal bichromate andlactic acid but free from an acid capable of dissolving part of theiron, said solution being maintained at a temperature of from about 90to 100 C.

5. The process which comprises subject ing wool in an iron vessel to theaction of a boiling solution containing sodium bichromate and an acidcomponent composed of lactic acid.

6. The process of dyeing wool which comprises treating that wool forabout halfan hour with a solution at a temperature of from about 90 to100 C. containing a bichromate and lactic acid, then adding to theresulting mixture a solution of a mordant dyestufi', and heating thebath at a temperature of from about 90 to 100 C. with the addition of anacid to exhaust the color.

7. The process of dyeing wool which comprises treating the wool forabout half an hour with a solution at a temperature of from about 90 to100 C. containing sodium bichromate and lactic acid, then adding to themixture a water solution of an rtho hydroxy-azo-dyestuff, maintainingthe resultingsolution in the presence of said wool at a temperature offrom about 90 to 100 C. with the addition of an acid to exhaust thecolor in the dye bath, and afterchroming the dyed wool with a bichromatesolutidn containing sulphuric and lactic acids.

8. The process of dyeing wool which comprises treating the wool in avessel having an inner surface of iron for about half an hour with asolution at a temperature of from about 90130 100 C. containing abichromate and lactic acid, then adding to the resulting mixture asolution of a mordant dyestufi, and heating the bath at atemperature offrom about to C. with the addition. of an acid to exhaust the color.

9. The process of dyeing wool which comprises treating the wool in avessel having an inner surface of iron for about half an hour with asolution at a temperature of from about 90 to 100 C. containing a sodiumbichromate and lactic acid, then adding to the mixture a water solutionof an ortho-hydroxy-azo-dyestufi', maintaining the resulting solution inthe presence of said wool at a temperature of from about 90 to 100 C.with the addition of an acid to exhaust the color in the dye bath, andafterchroming the dyed wool with a bichromate solution containingsulphuric and lactic 10. The process of dyeing wool which comprisesmaintaining 100. parts of wool in contact for about half an hour with aboiling solution containing about 2% parts of and then after-chromingthe dyed Wool with sodium bichromate and about 5 parts of about 2 partsof sodium biohromatgabout lactic acid, then adding a water solution 1part of sulfuric acid and about 4: parts of 1 containing'about 6 partsof 2,2f-dihydroxylactic amid. 1 4-sulf0-1,l-azonaphthalene, boiling there- In testimony whereof I afiix my signature. sulting solution forabout an hour with the addition of an acid to exhaust the color,-FRANCIS C. TELEN.

